fixup a whole steaming pile of insanity. When packages are configured,

they should be configured with --prefix=/usr and we then need to use
make DESTDIR=$(STAGING_DIR) install to get things installed into the
staging directory. The current situation for many packages, which use
--prefix=$(STAGING_DIR) results in the staging_dir paths getting compiled
into the binary itself.
This also adds in a pile of libtool fixups. Between broken pkgconfig,
broken libtool handling, and broken --prefix settings, its a wonder
things have worked as well as they have up till now.
-Erik